1. Field of the Invention
The present invention relates to a dual curing type composite resin for core build-up.
2. Description of the Conventional Art
In a case of fixing a dental prosthesis at a residual tooth, when the residual tooth is in an almost healthy state, this residual tooth is cut by a turbine so as to have an approximately truncated conical shape, and is used as an abutment tooth. However, when a residual tooth is remarkably damaged and only remains as a dental root portion, an operation to reinforce holding force of the abutment tooth is carried out by inserting a post into a root canal, implanting it, and core build-up model with a substance which substitutes a dentin. Thereafter, the abutment tooth is cut by a turbine so as to have an approximately truncated conical shape for use as a abutment tooth.
When such an abutment tooth model is built, a specific composite resin for core build-up has been generally used. This composite resin has high penetrability into a narrow part of a root canal and thus an abutment tooth can easily be built. Such the composite resin for core build-up (it may be called as only a composition hereinafter) is a photopolymerizable material, so that an operator can adjust viscosity of the composition by irradiating light for a proper time whenever the operator wants. Further, when an operator wants to complete polymerizing of the composition, the composition can be rapidly cured by fully irradiating light, and thus handling of the composition can be easily controlled.
On the other hand, when a post is implanted, a dual curing type composition, which is cured by photopolymerization and chemical polymerization, has been used (for example, refer to Unexamined Japanese Patent Publication No. H9-157126) in order to sufficiently cure a composition flowed into the inside of a root canal and a cavity bottom part where light hardly reaches. However, as for the conventional dual curing type composition, since polymerizing at the portion where light hardly reaches depends on only a chemical polymerization, an effect by a photopolymerization cannot be expected, and mechanical strength of a cured body may be lower than a designed value. Further, a time until the composition becomes capable of being cut by using a turbine to have a shape of an abutment tooth depends on a speed of a chemical polymerization of the composition flowed into a root canal. Thus, it is desirable for both an operator and a patient that the speed of the chemical polymerization increases within the range not to affect preservation property of a composition.